In vehicles such as automobiles, in order to improve the riding comfort felt by the occupant, there is a need for a vehicle structure which suppresses transmission of vibrations generated in various parts of the vehicle into the vehicle compartment as much as possible. In order to satisfy this requirement, the present applicant proposes, in Patent Literature 1 to 3, a technique for devising a joining mode of a bulkhead (reinforcement body) disposed in a frame that forms a closed cross-section, to the frame. The joining mode includes a rigid coupling portion in which the frame and the bulkhead are joined with each other while being in contact with each other, and a flexible coupling portion in which the frame and the bulkhead are joined with each other while interposing a damping member therebetween.
A vehicle includes a portion having a partitioned closed cross-section which is provided with two panels (frames) forming a closed cross-section extending in a predetermined direction, and a partition panel extending in the predetermined direction and disposed in the closed cross-section. Patent Literature 3 discloses a vehicle-body structure in which a bulkhead including the rigid coupling portion and the flexible coupling portion is incorporated in the portion having the partitioned closed cross-sectional portion.
The partitioned closed cross-sectional structure is adopted for, for example, a coupling portion between a center pillar and a side sill. In such a coupling portion, a request for suppressing deformation or vibration of the closed cross-sectional portion caused by the vibration of the vehicle is particularly high.